1. Field of the Invention
The present invention relates to a flame-retardant resin composition. More particularly, it relates to a flame-retardant resin composition having a flame-retardant comprising a zinc salt of a carboxylic acid incorporated to a polycarbonate resin.
2. Discussion of Background
By virtue of their excellent mechanical properties and thermal characteristics, polycarbonate resins are widely used industrially in the automobiles field, the office appliances field, the electronic and electrical field, etc. On the other hand, in recent years, there has been a strong demand for flame-retardancy, especially, of resin materials to be used in the applications to office appliances and house-hold electrical appliances. To meet such a demand, many flame retardants have been developed and being studied. Heretofore, for flame-retardancy of polycarbonate resins, chlorine- or bromine-containing compounds have been mainly used, and in many cases, antimony trioxide or the like has been used as a flame-retarding assistant in combination with such flame-retardants.
When a chlorine- or bromine-containing compound is used for flame-retardancy, the flame-retarding effect is relatively high, but noxious or hazardous substances will be produced during the incineration treatment or at the outbreak of fire, whereby emergency activities or fire extinguishing activities will be difficult, or an environmental pollution is likely to be brought about. Further, the chlorine- or bromine-containing compound has a problem that the heat stability is not adequate, and the mechanical properties tend to deteriorate by the heat history during the molding operation. Therefore, it is desired to develop a flame-retardant resin which contains no such chlorine- or bromine-containing compound or which has a relatively small content of such a chlorine- or bromine-containing compound.
It is an object of the present invention to solve such problems of the prior art and to provide a flame-retardant resin composition having excellent flame-retardancy.
Japanese Unexamined Patent Publication No. 90557/1977 discloses a thermally stable composition comprising an aromatic polycarbonate, a C.sub.1-24 carboxylic acid (non-anhydride) and a salt of a C.sub.1-24 carboxylic acid with a metal of Group II in the periodic table. However, this publication discloses nothing about a flame-retarding effect, although it discloses improvement of the thermal stability. Namely, this publication teaches nothing about improvement of the flame-retardancy by the use of a salt of a carboxylic acid with zinc.